O2 Sim question

**SilentTrouble** · 03-16-2011, 05:12 PM

So my car dumped to about 8 mpg on me recently and while i was looking for possible causes i found my 02 sims. I didnt install the sims the previous owner did and while I did not get SES (i never have for anything) it is showing up in the obd2 scans. My sims seen here (http://www.ftpp.net/images/CaspersEl.../104033-1.jpeg) have LED's on them presumably for verification of function.

One side had come loose, I plugged it back in and it lit up while the car was on (not running).... GREAT! On to the other side.

Not on, plugged in. So I grabbed the good one from the other side and plugged it in... no luck... took the one off the bad side and tried it on the good side. No luck either... Now what? My good one doesnt work on one side and the one from the bad side doesnt work on the good side.

I had a volt meter on so i tested the connection from the car. The connector from the car had voltage so I dont know where to go next. Any suggestions? What should the voltage be?

**pajeff02** · 03-16-2011, 05:21 PM

The rear O2 senders simply provide feedback to the PCM to tell it if the cats are working. They have nothing to do with your fueling. If for some reason you have sims plugged into your front O2 senders -- that is a huge problem and needs to be rectified immediately.

Other possible issues:

Dirty air filter, dirty MAF, air leak in the exhaust fooling the O2's into calling for more fuel, worn plugs, and of course... heavy right foot.

**SilentTrouble** · 03-16-2011, 05:37 PM

So only to prevent SES light... case closed

**pajeff02** · 03-16-2011, 05:55 PM

Originally Posted by SilentTrouble

So only to prevent SES light... case closed

Exactly. Forgot to mention, that if your front O2's are starting to go that can also affect fueling. Any access to a scanner so you can see your sensor output and fuel trims?